Perception of acceleration with short presentation times: can acceleration be used in interception?

To investigate whether visual judgments of acceleration could be used for intercepting moving targets, we determined how well subjects can detect acceleration when the presentation time is short. In a differential judgment task, two dots were presented successively. One dot accelerated and the other decelerated. Subjects had to indicate which of the two accelerated. In an absolute judgment task, subjects had to adjust the motion of a dot so that it appeared to move at a constant velocity. The results for the two tasks were similar. For most subjects, we could determine a detection threshold even when the presentation time was only 300 msec. However, an analysis of these thresholds suggests that subjects did not detect the acceleration itself but that they detected that a target had accelerated on the basis of the change in velocity between the beginning and the end of the presentation. A change of about 25% was needed to detect acceleration with reasonable confidence. Perhaps the simplest use of acceleration for interception consists of distinguishing between acceleration and deceleration of the optic projection of an approaching ball to determine whether one has to run backward or forward to catch it. We examined the results of a real ball-catching task (Oudejans, Michaels, & Bakker, 1997) and found that subjects reacted before acceleration could have been detected. We conclude that acceleration is not used in this simple manner to intercept moving targets.     

Testing the counter model for perceptual identification: Effects of repetition priming and word frequency

The counter model for perceptual identification (Ratcliff & McKoon, 1997) differs from alternative views of word recognition in two important ways. First, it assumes that prior study of a word does not result in increased sensitivity but, rather, in bias. Second, the effects of word frequency and prior study are explained by different mechanisms. In the present experiment, study status and word frequency of target and foil were varied independently. Using a forced-choice task, we replicated the bias effect. However, we also found several interactions between frequency and prior study that are in direct conflict with the counter model. Most important, prior study of both alternatives resulted in an attenuation of the frequency effect and an increase in performance for low-frequency targets, but not for high-frequency targets. These findings suggest that the effects of frequency and prior study are not mediated by completely independent mechanisms.     

Finite Frames Fail: How Infinity Works Its Way into the Semantics of Admissibility

Many intermediate logics, even extremely well-behaved ones such as IPC, lack the finite model property for admissible rules. We give conditions under which this failure holds. We show that frames which validate all admissible rules necessarily satisfy a certain closure condition, and we prove that this condition, in the finite case, ensures that the frame is of width 2. Finally, we indicate how this result is related to some classical results on finite, free Heyting algebras.     

Smells like cooperation? Unpleasant body odor and people's perceptions and helping behaviors

Scents are omnipresent in our daily world and they are of great importance as represented by the use of perfumes or fragrances in the work environment. Even though it has been argued that bad scents invoke negative judgments, we argued and demonstrated that a bad body odor elicits feelings of pity in others (Experiment 1) and increases prosocial behavior (Experiment 2). Further, we showed that only if a person is not held accountable for his own body odor this elevated other's prosocial behavior (Experiment 3). These findings provide a novel perspective on the way human body odor affects our perceptions and consequent behaviors.     

Epistemic dependence and collective scientific knowledge

I argue that scientific knowledge is collective knowledge, in a sense to be specified and defended. I first consider some existing proposals for construing collective knowledge and argue that they are unsatisfactory, at least for scientific knowledge as we encounter it in actual scientific practice. Then I introduce an alternative conception of collective knowledge, on which knowledge is collective if there is a strong form of mutual epistemic dependence among scientists, which makes it so that satisfaction of the justification condition on knowledge ineliminably requires a collective. Next, I show how features of contemporary science support the conclusion that scientific knowledge is collective knowledge in this sense. Finally, I consider implications of my proposal and defend it against objections.     

Training self‐assessment and task‐selection skills to foster self‐regulated learning: Do trained skills transfer across domains?

Students' ability to accurately self‐assess their performance and select a suitable subsequent learning task in response is imperative for effective self‐regulated learning. Video modeling examples have proven effective for training self‐assessment and task‐selection skills, and—importantly—such training fostered self‐regulated learning outcomes. It is unclear, however, whether trained skills would transfer across domains. We investigated whether skills acquired from training with either a specific, algorithmic task‐selection rule or a more general heuristic task‐selection rule in biology would transfer to self‐regulated learning in math. A manipulation check performed after the training confirmed that both algorithmic and heuristic training improved task‐selection skills on the biology problems compared with the control condition. However, we found no evidence that students subsequently applied the acquired skills during self‐regulated learning in math. Future research should investigate how to support transfer of task‐selection skills across domains.     

Multimedia instructions and cognitive load theory: Effects of modality and cueing

Background: Recent research on the influence of presentation format on the effectiveness of multimedia instructions has yielded some interesting results. According to cognitive load theory (Sweller, Van Merriënboer, & Paas, 1998) and Mayer's theory of multimedia learning (Mayer, 2001), replacing visual text with spoken text (the modality effect) and adding visual cues relating elements of a picture to the text (the cueing effect) both increase the effectiveness of multimedia instructions in terms of better learning results or less mental effort spent. Aims: The aim of this study was to test the generalisability of the modality and cueing effect in a classroom setting. Sample: The participants were 111 second‐year students from the Department of Education at the University of Gent in Belgium (age between 19 and 25 years). Method: The participants studied a web‐based multimedia lesson on instructional design for about one hour. Afterwards they completed a retention and a transfer test. During both the instruction and the tests, self‐report measures of mental effort were administered. Results: Adding visual cues to the pictures resulted in higher retention scores, while replacing visual text with spoken text resulted in lower retention and transfer scores. Conclusions: Only a weak cueing effect and even a reverse modality effect have been found, indicating that both effects do not easily generalise to non‐laboratory settings. A possible explanation for the reversed modality effect is that the multimedia instructions in this study were learner‐paced, as opposed to the system‐paced instructions used in earlier research.     

“Seeing is believing”: The effects of facial expressions of emotion and verbal communication in social dilemmas

In social dilemmas, verbal communication of one's intentions is an important factor in increasing cooperation. In addition to verbal communication of one's intentions, also the communication of emotions of anger and happiness can influence cooperative behavior. In the present paper, we argue that facial expressions of emotion moderate verbal communication in social dilemmas. More specifically, three experiments showed that if the other person displayed happiness he or she was perceived as honest, trustworthy, and reliable, and cooperation was increased when verbal communication was cooperative rather than self‐interested. However, if the other person displayed anger, verbal communication did not influence people's decision behavior. Results also showed interactive effects on people's perceptions of trustworthiness, which partially mediated decision behavior. These findings suggest that emotion displays have an important function in organizational settings because they are able to influence social interactions and cooperative behavior. Copyright © 2009 John Wiley & Sons, Ltd.     

The meta-ethical significance of experiments about folk moral objectivism

The meta-ethical commitments of folk respondents – specifically their commitment to the objectivity of moral claims – have recently become subject to empirical scrutiny. Experimental findings suggest that people are meta-ethical pluralists: There is both inter- and intrapersonal variation with regard to people’s objectivist commitments. What meta-ethical implications, if any, do these findings have? I point out that current research does not directly address traditional meta-ethical questions: The methods used and distinctions drawn by experimenters do not perfectly match those of meta-ethicists. However, I go on to argue that, in spite of this mismatch, the research findings should be of interest to moral philosophers, including meta-ethicists. Not only do these findings extend the field of moral psychology with new data and hypotheses, but they also provide tentative evidence that touches on the adequacy of theses in moral semantics and moral metaphysics. Specifically, they put pressure on arguments in support of moral realism.